Isidore was born in Madrid, in about the year 1070, of poor but very devout parents, and was christened Isidore from the name of their patron, St. Isidore of Seville. Isidore spent his life as a hired hand in the service of the wealthy Madrilenian landowner Juan de Vargas on a farm in the city's vicinity.[8] He shared what he had, even his meals, with the poor.[9] Juan de Vargas would later make him bailiff of his entire estate of Lower Caramanca.

It was said that he stood two meters tall.

Isidore married Maria Torribia, known as Santa María de la Cabeza in Spain because her head (cabeza in Spanish) was kept in a chapel[10] and possibly brought out in processions to summon rain,[11] although she has never been canonized, pending confirmation by Pope Francis. Isidore and Maria had one son.[8] On one occasion, their son fell into a deep well and, at the prayers of his parents, the water of the well is said to have risen miraculously to the level of the ground, bringing the child with it. In thanksgiving Isidore and Maria then vowed sexual abstinence and lived in separate houses. Their son later died in his youth.

Isidore died on 15 May 1130[citation needed], at his birthplace close to Madrid although the only official source places his death in the year 1172.[12]

In the morning before going to work, Isidore would usually attend Mass at one of the churches in Madrid. One day, his fellow farm workers complained to their master that Isidore was always late for work in the morning. Upon investigation, so runs the legend, the master found Isidore at prayer whilst an angel was doing the ploughing for him.[9]

On another occasion, his master saw an angel ploughing on either side of him, so that Isidore's work was equal to that of three of his fellow field workers. Isidore is also said to have brought back to life his master's deceased daughter, and to have caused a fountain of fresh water to burst from the dry earth to quench his master's thirst.[9]

One snowy day, when going to the mill with corn to be ground, he passed a flock of wood-pigeons scratching vainly for food on the hard surface of the frosty ground. Taking pity on the poor animals, he poured half of his sack of precious corn upon the ground for the birds, despite the mocking of witnesses. When he reached the mill, however, the bag was full, and the corn, when it was ground, produced double the expected amount of flour. (In the original story it was wheat, as corn was not introduced to Spain until the 15th century).[9]

Isidore's wife, Maria, always kept a pot of stew on the fireplace in their humble home as Isidore would often bring home anyone who was hungry. One day he brought home more hungry people than usual. After she served many of them, Maria told him that there simply was no more stew in the pot. He insisted that she check the pot again, and she was able to spoon out enough stew to feed them all.[13]

On 2 April 1212, after torrential rains had exhumed cadavers from cemeteries in Madrid, his body was discovered in an apparent state of incorruptibility.[12]

He is said to have appeared to Alfonso VIII of Castile, and to have shown him the hidden path by which he surprised the Moors and gained the victory of Las Navas de Tolosa, in 1212.[9] When King Philip III of Spain was cured of a deadly disease after touching the relics of the saint, the king replaced the old reliquary with a costly silver one and instigated the process of his beatification.[14] Throughout history, other members of the royal family would seek curative powers from the saint.

The number of miracles attributed to him has been counted as 438.[14] The only original source of hagiography on him is a fourteenth century codex called Códice de Juan Diácono which relates five of his miracles: 1. The pigeons and the grain. 2. The angels ploughing. 3. The saving of his donkey, through prayer, from a wolf attack. 4. The account of his wife's pot of food. 5. A similar account of his feeding the brotherhood. The codex also attests to the incorruptible state of his body, stating it was exhumed 40 years after his death.[15]

In 1696, his relics were moved to the Royal Alcazar of Madrid to intervene on behalf of the health of Charles II of Spain. While there, the King's locksmith pulled a tooth from the body and gave it to the monarch, who slept with it under his pillow until his death. This was not the first, nor the last time his body was allegedly mutilated out of religious furor. For example, it was reported one of the ladies of the court of Isabella I of Castile bit off one of his toes.

In 1769, Charles III of Spain had the remains of Saint Isidore and his wife Maria relocated to the San Isidro Church, Madrid.[12] The sepulcher has nine locks and only the King of Spain has the master key. The opening of the sepulcher must be performed by the archbishop of Madrid and authorized by the King himself. Consequently, it has not been opened since 1985.[17]

Saint Isidore is often portrayed as a peasant holding a sickle and a sheaf of corn. He might also be shown with a sickle and staff; as an angel plows for him; or with an angel and white oxen near him.[13] In Spanish art his emblems are a spade or a plough.

The story of St. Isidore is a reminder of the dignity of work, and that ordinary life can lead to holiness.[18] Legends about angel helpers and mysterious oxen indicate that his work was not neglected and his duties did not go unfulfilled. St. Isidore's life demonstrates that: If you have your spiritual self in order, your earthly commitments will fall into order also."[19]

The house of his master, Juan de Vargas, in Madrid is now a museum, popularly known as the "Casa de San Isidro". It houses temporary exhibitions on the history of Madrid, as well as on the life of the saint.[20] It is not to be confused with the aforementioned San Isidro Church. Not only does this museum contain a chapel built upon the place where Isidore lived and died, but also the well where his son fell and was saved.

This is in the chapel built where he lived and died, in the Saint Isidore Museum in Saint Andrew's square in Madrid.

The date of his liturgical feast, which, though not included in the General Roman Calendar, has been celebrated for centuries in several countries and dioceses, is 15 May.[21] Many towns venerate St Isidore and his wife Saint Maria Torribia with processions in which the fields are blessed.

One of the most celebrated holidays of Madrid is held on May 15, the Feast Day of San Isidro who is the city's patron saint as well as the patron saint of farmers. The traditional festival and feast are held in an open-air area known as the Pradera del Santo. In the afternoon, the image of San Isidro and his wife, Santa Maria de la Cabeza, are paraded through the streets, from Calle del Sacramento to the Plaza de la Villa, via Calle del Cordon.[20]

The feast in honor of San Isidro is declared of National Tourist Interest in Andalusia and is one of the most important celebrations in province of Malaga. The fiesta is very popular in region of Alameda because San Isidro is a patron of the town.[22]

Celebrations honoring both saints are also held elsewhere on the islands. For years, the Alicantine locality of Castalla has been celebrating the Fair of San Isidro, where numerous companies display their products in a playful and festive atmosphere. A medieval swap meet and mechanical attractions are especially popular.

A large celebration is held in Estepona, (near Marbella) in Andalucia, where locals celebrate the day by drinking a mix of brandy and a popular energy drink which is named in his honour. This has led to St. Isidore often being termed as the patron saint of krunk (because of the name of this combination drink in the US).

The Romería festival in Almogia, a pueblo blanco in the campo north of Malaga (about halfway between Malaga and Antequera) in Andalucia, celebrates San Isidro, its patron saint, on the middle weekend of May with a fiesta carnival. Floats from the surrounding farming communities, accompanied by traditionally dressed ladies in flamenco dresses and caballeros on dancing horses, sing and dance from Almogia to the Romería ground a few kilometres north of the village and the festival includes music, traditional horse races, a bar for horses as well as their riders, and much parading of costume and finery. The best-dressed float is awarded a prize.

15 May is San Isidro Day in Cuz-Cuz, about five kilometers from the city of Illapel, Choapa province, in the Coquimbo region of Chile. If the day falls on a Monday, the following Sunday is celebrated. Celebrations begin at noon with a Mass, followed by a procession and Chilean dances.

The residents of San Isidro de Carampá of Ayacucho in the city of Lima celebrate a San Isidro festival. The First Society of San Isidro de Carampá organizes the festival, along with the Butler and the Adornante festivals. In the evening, after the celebration of the Mass, a procession moves to the house of the Adornante. On the next day, Central Day, another Mass is said, this time celebrated by the Butler. Another procession is held, followed by a festival.

The Kangga Festival is held on his feast day in Mogpog, Marinduque (the island province best known for its Moriones Festival every Holy Week). The festivities highlight Filipino farming traditions, as well as in thanksgiving for a good harvest and the town's continuing prosperity.

The Nabas Bariw Festival is celebrated in Nabas, Aklan, every 12–15 May as St. Isidore is the town's patron saint. The feast also showcases the town's bariw products such as hats and mats as well as the town's unique attractions.

St Isidore is fêted in the towns of San Isidro and Talavera, Nueva Ecija. The province is often referred to as the “Rice Granary of the Philippines", and its principal crops aside from rice are corn and onions. Celebrations begin a week before the feast itself, including daily novenas, Masses, processions, entertainment and a funfair (perya).

St. Isidore celebrating feast on May 15–16 of Barangay Teguis Poro Cebu.

St. Isidore's feast is also celebrated in the town of Lezo, Aklan every 14th-15 May. Lezo is an agricultural town, giving thanks to Sr. San Isidro Labrador for their bountiful harvest.

In 1947, at the request of the National Catholic Rural Life Conference, he was officially named patron of farmers, with a feast day on 10 May in all dioceses of the United States, with a proper Mass and Office. When St Isidore's feast was first inserted into the calendar for the United States in the year 1947, the feast day of Saint John Baptist de La Salle was still being celebrated on 15 May, with the result that the celebration of his feast was assigned to 22 March.

With the 1969 revision of the General Roman Calendar, the memorial of Saint John Baptist de la Salle was moved to his day of death, 7 April, and Saint Isidore's was restored to the 15 May date and celebrated as an optional memorial. In some places within the US and Canada, his feast is celebrated on 25 October, and other locations and some Traditionalist Catholics in that area, though not elsewhere, keep the 22 March date.